Sounds like you're still going to the app and then trying to find the setting. Don't do that, find the setting and then find the app.
If I understand correctly you're doing:
Search for app -> go into app's settings -> click file permissions -> see only media options -> no profit
Which to be fair makes the most sense, but just don't because it wont work lol (I did this first too).
You need to:
Search for "all file access" in the generic settings app (I don't know if you can even find it manually, so to save time I just use the search feature) -> select this, get into a menu with a big list titled special access -> select first option "all file access" -> find the app in question (music bee in this case) -> ensure the little flip switch is blue (toggled to the right, meaning active) -> profit

Sadly Music bee is not in this list of apps under "all file access"
Same problem here. When I run
MusicBee WiFi Sync (MWS) for the first time, Android prompts to "Allow MWS to access photos and media on your device." This is because the app is categorized as a
media app, so Android will not permit it to have access to every folder on the device (i.e., no root folder). As noted above, Android will not even let the user grant permission to MWS to access the root folder. This would not be a problem except that MWS will not allow the user to select a folder other than the root of the device.
Something has to change: Either MWS must be classified as a general "files" app (not just media) so Android will allow it to access the root, or MWS has to accept a subfolder. Personally, I prefer the latter since there is no need for MWS to access every folder and file on my phone. I'd prefer to give it a
MusicBee subfolder to play with.
As a software developer, I know not everything is as simple as it seems, but it seems that it should not be too difficult to change MWS to operate in a subfolder instead of the root. Which brings me to the post below...
I forked off from the main repo and made it compatible with Android 13 if you want to try it https://github.com/mayallst/MusicBeeWifiSync/compare/master...akarabak:MusicBeeWifiSync:development. Tested on Pixel 7 and Xperia 1 III.
Most people probably do not want to wrestle with Android Studio and gradle (which are both horrible) and build an APK to sideload on their phones, perhaps you could submit a pull request with your fix to the original repo? I'm sure the author would be ecstatic to have a fix for this and close out this thread.
As for Resilio, I used it a few years ago and it was a great tool. An excellent (and free) alternative is Syncthing.
Android:
https://play.google.com/store/apps/details?id=com.nutomic.syncthingandroidWindows:
https://syncthing.net/SyncTrayzor is a great Windows shell around Syncthing:
https://github.com/canton7/SyncTrayzor