TikTok posts now schedule from the composer. Connect TikTok and a video or a photo slideshow queues like anything else you write.
Set it up the way TikTok expects
One video, or up to 35 images as a slideshow, with 2,200 characters of caption. Set the privacy level for that post, turn comments, Duet and Stitch on where your account allows them, and declare a paid partnership the way TikTok asks.
Size, length and frame rate are checked for you before the video goes out, with the length read from your own account.
The preview plays in the 9:16 frame the app gives it, so the cover and the words get checked together. The TikTok page has the rest.