Hello @Salzburg and welcome to the forums
I sometimes wonder if all of this technology that is meant to make it easier to connect also plays a part in being less committal as it's now so easy to both make and to cancel plans. I find many of my plans with friends involve a lot of last minute rescheduling or cancelling, and while I try not to do that myself I still find I do on occasion.
I also know that I've been that person who has wanted to befriend someone but has backed out on plans which has essentially ruined the chances of it blossoming into a friendship. For me it's been a mixture of social anxiety and outside stress, though that's not an excuse and I look back on those times with regret.
It's completely understandable to be frustrated, I wonder if you might be able to be open with this person and let them know that you're still wanting to spend time with them and to get to know them better, but that it's frustrating that they can't commit to plans, and perhaps ask if there's a way you can make scheduling something a bit easier for them? What do you think?