I finished rendering a video that lasted like 3hrs, when finished it said “make sure SeeMusic can access your photos”, is my render lost?

1. Ok, for the issue of saving the file, my previous response is still the correct solution I can offer at this time.

2. For the issue of it slowing done and crashing - this would simply be that your device does not have enough memory / processing power for the render. SeeMusic is primarily intended to render on computers / laptops. If you have to render on a phone, try using the following Render Settings:

- Resolution: 720p

- Framerate: 30

- Quality: Medium

That should help the renders finish without crashing and quicker.