There are few ways:
- find abr/tpl file in Safari, and open it in Artstudio
- if file is Safari is zipped, unzip it first using for example free iZip app.
- open it from email
- drag and drop it
- use Airdrop to transfer it from other device
- use “import abr/tpl” option in Artstudio Pro and import it from iCloud Drive
- if you store them in Google Drive or Dropbox, the last point may not work, so you have to use Google Drive/Dropbox app - select abr file there, find “Open In” option, and choose Artstudio Pro