Hello @Doriane 
Welcome to DevKinsta community!
The DK0029 error (during the site pull/import site from MyKinsta) usually means DevKinsta is unable to create a MySQL dump on the remote server.
So that we can check and review this case further, could you please send (DM) me the main.log file of your DevKinsta application? You can check here to see how to see/get that main.log file.
Cheers,
Agus