Hello Raquold,
The schedule for this project is to complete the last level around October 2020 - depending on my development speed, it could delay one or two months, however, it's safe to assume the project will reach its alpha version before the end of 2020.
If things go as planned, the project will undergo a series of beta testing and tweaking during the first quarter of 2021 - which I believe at that time, the game will have a definite style and theme - I think it will be an appropriate timing for me to add ambient / theme music into the game. You could contact me then, that is, if you are still interested in joining the project.
I'm sorry I couldn't give you a confirmation for collaboration right now, however, I think we could keep in touch, if you have anything you found may suit the game's atmosphere (even just a 15~30 seconds music clip), I'm willing to give it a try and see how things go.
Thank you again for your interest and I wish you all the best in your career. =)