You can only invest in crowdfunded companies when they have a funding round, hence the reference to round 1, round 2 etc. These are not publicly traded shares so you can’t buy them unless the company in question is selling shares. You can’t sell these shares either unless the company IPO’s (goes public) or is bought by a bigger company which could take many years and might never happen if they go bust.
Index tracker funds are available on freetrade and a good option if you’re just starting out. These funds invest in many companies and you won’t lose all you’re money if some of these companies go bust.