This is excellent. Well done, without knowing more, if I see correctly you are based in the US or are willing to consider US investors?
A) This is great because in the US under certain conditions (please inform yourself to ensure you oblige to the legal standards) direct marketing is allowed. I highly recommend that you reach out directly to investors, via email and phone calls. This will probably have the largest chance of success since it is very targeted and does not cost much. To reach out you can research contacts yourselves or alternatively you can use B2B access platforms or B2C access platforms.
B) You can hire an agency who does this for you, so someone who otherwise focuses on marketing but gets you lead for investors instead
C) experiment with digital marketing and run ads
D) contact directly others in similar markets who fundraised using your platform and get their tips for free. It often helps to understand what actually worked for them and you have the common connection of using the same platform

Of course one would need to better understand your situation, so the advice can be more tailored, but I think you should be very good to go with A)