Have you tried setting up the camera like in this video?
To avoid seams, Post Processing settings are applied.
Settings Post Process for Camera 360:
- Vignete: 0
- Exponecial Heigh Fog : Volumetric Fog Off
- Ambient Occlusion: 0
- ScreenSpaceReflection: 0
- Bloom: 0
Camera 360 settings: Aspect Ratio: 1:1
Output: Frames: 3614 frames
Rendering time: ~ 1 hour 33 minutes
Rendering 1 frame: ~ 1-2 second
Render Target Texture (Quality): 4096 Px.
Size Output Image: JPG, 7680x7680
I very often apply quality to get 8K and 4k video.