Need Help with International Tax Compliance

Hi first time posting. Launched an MVE and have received international investment. I am quite lost on what to do from here as the investment came out of the blue. The business as currently set up is located within the states and taxed as an S Corp. I have read that it is not the most viable option for foreign investment as well we are planning on a second round in march. Would anyone have good resources or have gone through something similar? Any advice would be appreciated.