Opinions on the Delian Tomb (Part 1)

So I have recently bought this adventure for the sole purpose of running part 1 as an introduction to some players who wanted to try out the system, and I wanted to try it out as well. I read that part 1 could be run as a one shot(great!) and that i could be balanced for 6 players(even better!). So we tried it and... it kinda sucked (for me, not that much for the players) , but I already signed up for running it again at a fair a few days from now, so aside from being an opinion on the adventure(only part 1) this is also me asking for advice to make it more... bearable.

Some info about myself: I have been gming for a year and a half, mostly lancer (so I enjoy a good crunchy combat) and mostly using a vtt to automate some stuff, I wanted to try out the system due to its tactical nature(as I said, love myself a good combat).

Issue 1: 4 Combats. Four. With 6 players (maybe that was my first mistake) every single one of them took upwards of 1 hour to 1 hour and a half. That's about a minimum of 6 hours doing calculations, but it ended up being worse than that. In 6 hours, we managed to REACH D4, and I had them resolve the situation in a few rolls because we were definitely out of time and everyone was bogged down by 3 back to back combats (mostly me) and it still took a total of 6 hours of running. How can I make it shorter? Is it even possible to run this thing with 6 players and not go mad?

Issue 2: Tracking stuff in combat. Encounter sheets suck (I guess this is a popular opinion after browsing this stuff a bit) and that combined with this being my first time running a complex game by tracking stuff on paper, it got messy real fast. Having to whip out 22 miniatures and color code them by group, was basically an impossible ask for me, so for the map and tokens, I used a vtt and cast my screen on a big TV table, and things still got very messy. Admittedly it might be a bit of a skill issue, but this is supposed to be run by someone who has no experience in ttrpgs! How? This wouldn't even be that much of an issue if it wasn't for the fact you have to do this crazy tracking and billion enemy turns and actions for 4 COMBATS IN A ROW, the mental wear was just insane. Is there any recommendation on vtts or tools I can use for automation? Codex looks cool but does it lend itself to in person play with a vtt for maps and tokens?

Issue 3: Too. Many. Books. I get it, it makes stuff more organized, and I wouldn't know a better solution, but damn, tabbing 3 different pdfs(adventure, encounters and rules reference) as well as a fourth tab having the vtt because as I said before, no way in hell I can find that many fitting minis and color code them and not lose track of who is who, it makes everything feel like I'm cross referencing 15 billion documents trying to find a mathematical formula or smth, it just adds on to the mental load. Having to tab into the encounter book to check the ability, then the vtt to move the token, then the rules reference to check whatever dazed means, then having to explain what potency is from the adventure book, just feels like a big mess.

Issue 4: 6 Player balancing. Yeah the book tells you to add some enemies, but it doesn't tell you where to put them, when to put them in and the encounter sheets don't even have room for them some times. Plus I felt like there were already plenty of enemies acting even without the extras. With the extras I just kept going "wait, I still have to move this many guys? Damn"

I genuinely want to like this tutorial, and run it again, or perhaps find a more suitable one shot, but I just had to get this out of my system because I barely enjoyed my time running this for the first time