Use h265/HEVC for your Quest 2, up to 8k - Always use h265 if your system/device supports it.
I know you mentioned 4k h264 but in general also never use h264/AVC larger than 4K unless you have a reason to, in VR these are commonly 1920p 2048p 2160p*. Side-by-Side
VR h264 2160p will already start giving issues on many systems and devices.
VR 1920p = 3,840 x 1,920 pixels
TV 2160p = 3,840 x 2,160 pixels
VR 2160p = 4,320 x 2,160 pixels - This is outside official AVC MPEG-4 supported specs. - *4,096 x 2,160 does work.
If possible, use a download manager to prevent incomplete files.
(jDownloader and Ninja Download Manger don't work with our website)