UpdateManager.cs

public class UpdateManager : MonoSingleton<UpdateManager>
    {
        private string baseUrl = "http://localhost:9876/api/v1/";
        private List<LCAPIAssetListResult> remoteAssetList = new List<LCAPIAssetListResult>();

        void Awake()
        {
            StartCoroutine(GetAssetListFromServer());

            // AssetBundle pipeline:
            // Put some asset in DynamicAssets folder
            // Make it an asset bundle in editor
            // Build asset bundle
            // Put the asset bundle in StreamingAssets folder
        }

        IEnumerator StartUpdating()
        {
            Debug.Log("Start updating...");

            string assetData = ObscuredPrefs.GetString("AssetData");

            var localAssetList = JsonConvert.DeserializeObject<List<AssetPlayerPrefModel>>(assetData);

            if (localAssetList == null || (localAssetList.Count == 0))
            {
                localAssetList = new List<AssetPlayerPrefModel>();
            }

            // First, load all dynamic assets that are included in the project
            var streamingAssetsDir = new DirectoryInfo(Application.streamingAssetsPath);
            foreach (var fileInfo in streamingAssetsDir.GetFiles())
            {
                Debug.Log($"Found file in streaming assets: {fileInfo.Name}{fileInfo.Extension}");
                if(fileInfo.Extension == ".meta")
                    continue;

                // Get local version of this file
                var localAsset = localAssetList.Find(x => x.Name == fileInfo.Name);
                if (localAsset == null)
                {
                    Debug.LogWarning($"Asset {fileInfo.Name} was not found in player prefs.");

                    // When its not found, add it
                    // Assume its version 0
                    localAsset = new AssetPlayerPrefModel() { Name = fileInfo.Name, Uri = $"{baseUrl}AssetDownload/{fileInfo.Name}", Version = 0 };
                    localAssetList.Add(localAsset);
                }

                // Get remote version of this file
                var remoteAsset = remoteAssetList.Find(x => x.Name == fileInfo.Name);
                if (remoteAsset == null)
                {
                    Debug.LogError($"Asset {fileInfo.Name} was not found on remote server.");
                    continue;
                }

                // Compare versions with local/remote
                if (localAsset.Version != remoteAsset.Version)
                {
                    Debug.Log($"Version mismatch on asset {localAsset.Name}. Local: {localAsset.Version} Remote: {remoteAsset.Version}");

                    using (var www = WWW.LoadFromCacheOrDownload(localAsset.Uri, remoteAsset.Version))
                    {
                        yield return www;

                        if (!string.IsNullOrEmpty(www.error))
                        {
                            Debug.Log($"Error while downloading/caching asset {localAsset.Name}. Error: {www.error}");
                            yield return null;
                        }

                        Debug.Log($"Asset {localAsset.Name}(ver {remoteAsset.Version}) successfully updated and cached.");
                        localAsset.Version = remoteAsset.Version;
                    }
                }
                else
                {
                    Debug.Log($"Asset {localAsset.Name} is up-to-date!");
                }
            }

            Debug.Log("Saving asset data...");
            SaveAssets(localAssetList);
            Debug.Log("Update complete!");

            AuthManager.Instance.OnAssetUpdateComplete();
        }

        IEnumerator GetAssetListFromServer()
        {
            Debug.Log("Get file list...");

            var request = UnityWebRequest.Get($"{baseUrl}Asset");
            request.downloadHandler = new DownloadHandlerBuffer();

            yield return request.SendWebRequest();

            if (request.isNetworkError || request.isHttpError)
            {
                Debug.Log("Error requesting asset list from server!");
                yield break;
            }

            string result = request.downloadHandler.text;
            Debug.Log(result);

            var remoteAssets = JsonConvert.DeserializeObject<LCAPIAssetList>(result);
            if (remoteAssets == null)
            {
                Debug.LogError("Error retrieving asset list from server!");
                yield break;
            }

            Debug.Log($"Got remote assets: {remoteAssets.Result.Count} assets.");
            this.remoteAssetList = remoteAssets.Result;

            StartCoroutine(StartUpdating());
        }

        void SaveAssets(List<AssetPlayerPrefModel> list)
        {
            string serializedAssets = JsonConvert.SerializeObject(list);
            ObscuredPrefs.SetString("AssetData", serializedAssets);
        }