Introducing 3 adult cats

Hey fellow cat lovers,

I recently moved in with a friend of mine and she has 2 cats (Bonded pair, both female, 7years old). I myself have one cat (male, 4 years old). In this case there's no real "resident cat" because we both moved into the new space together.

We're going through the process of trying to introduce them, and I'm looking for some advice/some success stories. We have 2 safe spots- the bonded pair have the basement and my cat stays in my room while we let one or the other out. When we had the door closed, the bonded pair would come and swat at my cat, so I put up a child gate with clear storage boxes in front of them for a barrier, which seems to be working much better.

My cat wants to be friends so bad, he chirps at the door when a cat walks buy, meows for their attention.... Etc. the girl cats want nothing to do with him, and have even started getting a little spicy with each other.

I've read a bunch of stuff online about scent swapping and location swapping, I'm just wondering when is the right time to move forward. We tried putting the food bowls by the door but the girls wouldn't eat. And how much hissing is normal during this process? They'll come up to the door or of curiosit, but then start growling or hissing and then walking away.

I just want them to get along eventually, but I feel like we're not doing something right. I hate seeing them stressed out 😭