Okay.
A couple things...
1. Your part 2a. says you "Create 2 new character slots". Are you saying you're right clicking on Characters, and selecting New Character? If that is what you're doing, you're most likely going to be missing some things that the Quick Setup Wizard is otherwise going to do for you automatically. For example,
Virtual Files are not going to automatically be applied to your manually-created Characters, and then because of that, ISBoxer will not be checking the launcher config to make sure it won't hang on initializing (in other words, you could be specifically avoiding the fix). Instead of creating them before using the wizard, just type in a Character Name and select the Game/Game Profile during the wizard.
2. Your part 4 says "Launch from Inner Space". It's possible to launch SWTOR directly from Inner Space but without using ISBoxer, by selecting your "SWTOR Default Profile". You should be selecting your Character Set name under "ISBoxer Character Sets" from the Inner Space menu.
So with that said, do something like this ...
1. Open ISBoxer Toolkit
2. File, Clear (use Save As first if you'd like to back up what you've already attempted)
3. Wizards, Quick Setup Wizard (at this point, your ISBoxer Toolkit profile is BLANK)
-- select SWTOR
-- add 2 characters
-- name team
--
none of the rest of the settings have any effect on the launcher making the Play button available. completing the rest of the wizard as you've described is fine.
4. Export to Inner Space
5. From the Inner Space menu "ISBoxer Character Sets" select your new team
The first launcher should open, and the Play button should light up.
If the Play button does NOT light up, then at this point go into the Help menu in ISBoxer Toolkit, and get me "Compatibility diagnostics" from the launcher. Paste the diagnostics to a paste site (e.g.
https://ybin.me) and give us the URL to the pasted contents.