Legality and Standard Finders Fee for Introduction?

My newly incorporated company introduces people/companies together, and if they earn money together I get paid. I broker meetings. In this particular deal, I have generated interest on both sides of 1) a start up apparel company with a unique line never seen before with 2) the owner of a 20 year apparel company with a huge facility, credibility, creative team and money to get the line completed as well as distributions channels. If they agree to partner, the start up would be giving up some % ownership of their company and they have major industry distribution channels too. Both are Florida based and I need to know if this is legal for me to do or must I be SEC licensed? Neither company is publicly traded. Money to develop and market may come from all parties or possibly more from the 20 year company~this has not been established yet. This line is so unusual, the 20 year owner said it was critical to hit the market big so it's not stolen by some huge company. The start up signed a non circumvent agreement.
Is this legal to earn a Finders Fee for me generating interest and introducing both parties? They will negotiate the details. I may help a little. Should I be paid on both sides or just one since they all will make money once launched? And, if so, since it will not be earning money till its launched into the market, what would be a standard fair finders fee? Is 5% dormant ownership of the company fair? or 5% future earnings? or a combination? Is there a standard? Since there would be no lump investment made how do I get fairly paid especially if it turns out to be a multi million dollar breakthrough brand? Any advice would be greatly appreciated. Thanks, CB