I'm not very familiar with Songsterr but from what I can see at that link I would recommend downloading Guitar Pro files from ultimate-guitar.com and displaying

I'm not very familiar with Songsterr but from what I can see at that link I would recommend downloading Guitar Pro files from ultimate-guitar.com and displaying them in Tuxguitar (https://www.tuxguitar.app/ https://www.tuxguitar.app/) which is free and open source