409 Conflict when calling sharing/get_shared_link_metadata

Yes, I'll give you all information about my case, maybe there is another way to achieve what I need.

I'm developing a new APP that stores some information into app users dropbox account, this works fine. Also, this app needs to access to a shared folder from my dropbox account to read some files, but I'm getting "SHARED_LINK_ACCESS_ERROR" error when I try to read from app.
Scoped app (App folder) is automatically set with selected permissions.

I'm using Java SDK 2.

    public String getPublicFileContent(final String sharedUrl, final String folder, final String filename) {
        String result;

        try (final DbxDownloader<SharedLinkMetadata> dropboxSharedLinkFileDownloader = dropboxClient
                .sharing()
                .getSharedLinkFileBuilder(sharedUrl)
                .withPath(getPath(folder, filename))
                .start()) {
            // Obtain input stream from file
            final InputStream fileInputStream = dropboxSharedLinkFileDownloader.getInputStream();

            // Read input stream
            result = new String(fileInputStream.readAllBytes(), StandardCharsets.UTF_8);
        } catch (final DbxException e) {
            log.error("[DROPBOX] Error al accssing public file '{}' - '{}' - '{}'. Error: ", sharedUrl, folder, filename, e);
        } catch (final IOException e) {
            log.error("[DROPBOX] Error reading public file '{}' - '{}' - '{}'. Error: ", sharedUrl, folder, filename, e);
        }

        return result.toString();
    }

  Error:

{
  "cause" : null,
  "stackTrace" : [ {
    "classLoaderName" : null,
    "moduleName" : "java.desktop",
    "moduleVersion" : "17.0.6",
    "methodName" : "run",
    "fileName" : "EventDispatchThread.java",
    "lineNumber" : 90,
    "nativeMethod" : false,
    "className" : "java.awt.EventDispatchThread"
  } ],
  "requestId" : "5bc7ef1fdb6d4731a41186a86e390b3f",
  "userMessage" : null,
  "errorValue" : "SHARED_LINK_ACCESS_DENIED",
  "message" : "Exception in 2/sharing/get_shared_link_file: SHARED_LINK_ACCESS_DENIED",
  "suppressed" : [ ],
  "localizedMessage" : "Exception in 2/sharing/get_shared_link_file: SHARED_LINK_ACCESS_DENIED"
}

If there is some error in my configuration or how I try to access to the file, pls tell me.