1. Find this folder on your phone:
Phone\Android\data\www.townofmagic.com\files\saves
This can usually be done using a regular file manager, which shows the files in the phone's memory.
2. This folder should contain save files. Copy them to some folder accessible from your computer or send these files to your Google. Drive
3. Go to your computer and place the save files in the game saves folder (game\saves).
Often, step 1 can be performed directly from the computer by connecting the phone to the computer via USB and opening it as an external drive.