Bitforex. It's the first time I used that exchange and I actually really like it. It has two-factor authentication with both your phone and Google Authenticator. Just set up your account and then go through all the security settings before doing anything. Then just transfer BTC, ETH, or USDT into your wallet. The pair is listed under OMI/USDT, so you will have to convert to USDT to buy it. On that note, the conversion fees on Bitforex were VERY low compared to others.What exchange are you using for OMI? Only thing I have is coinbase but I can't purchase through them?
EDIT: here is a good site describing how to buy and just an overview of OMI and Veve
An NFT project called Ecomi (token OMI) has been quietly brewing in the background, aiming to bring the VEVE (pronounced “ve-ve”) app-based marketplace mainstream with premium licensed digital collectibles. With VEVE, users can obtain common, rare, or one-of-a-kind digital collectibles...