The link to download TemplateToaster v8 Beta is up to date and last modified two days ago.
The 'btn, alert, container' classes are supported in v8 Beta and 'collapse, tooltip' classes are used as default as in Bootstrap. Currently, v8 Beta uses Bootstrap v4.1.3, in future build we will provide support for latest Bootstrap version.
TemplateToaster provide support for Joomla 2 and Joomla 3 versioned templates. Support for Joomla 4 templates will provided in future build of TemplateToaster, after stable release of Joomla 4 as currently Joomla 4 is in Alpha Stage