You could use some free online service to grab the videos. For instance, the one I use often is Tikcd.com . Below are the instructions:
Go to the TikTok site, open your account and find your video. Copy its URL by clicking on the “Share” button at the right-hand side of the video thumbnail. Tap the “Copy Link” on the popup menu to save the video URL.
Go to Tikcd.com.
Paste the URL to the input box. Tap the “Search” button to get the video thumbnail on the Download page.
Select a video resolution to save the video, or
If you like the MP3 audio, you could choose an audio bitrate, convert the video to MP3 audio.
Tap the “Download” button to save the video or MP3 audio.