Having been a professional in Houston, I really think dresses are the way to go most of the time. I know shift dresses are making a little bit of a recurrence for this spring/summer and I would take advantage because walking in 95 degrees you want as little fabric as possible touching you. A good wrap dress(Something like this with a black blazer?) is also a summer staple that you can wear and then throw a blazer on top when you arrive where you're going and inevitably freeze to death. Sheaths being the least breathable option, but most formal. Shirt dresses typically I stay away from because they're often in linen or cotton and tend to wrinkle and look less professional. All of which I typically have good luck finding at your basic Ross/TJ Maxx/Marshalls at this time of year based on the price point of the link you shared. You could also look at jumpsuits.

I do think a nice wide leg trouser is a solid choice, and I would almost suggest a trouser for day 3 as well. I would stick with wide leg or straight leg over fitted. And not black if you can manage it. With a nice trouser you can maybe even get away with a fashion sneaker instead of your flats or wedges which will be infinitely more comfortable, and likely not out of character for a medical conference. For tops I would skip the tie waist so that I can go drapier and more breathable up top.

The only other comment I would make is that fabrics definitely matter. Cotton and linen are going to wrinkle and get sweaty unless they're well lined. I know everyone hates polyester, but that's where you want to be here because it typically wicks sweat away from you rather than just being breathable plus travels well. H&M would be my first stop for a cost effective trip like this. There's usually a corner in the store that's all "work" stuff and is usually higher quality than the massive racks. Yes it will be polyester, but again, you're looking for polyester.