Mailster integration or email template for better emails design

Hello! I need support to integrate the plugin Mailster to use the plugin templates with PremiumPress emails.
(When I try to config the Mailster plugin, I can’t acces to PremiumPress control panel, it cause a infinite loop)

Or I need to know a method for modify the website email design templates.

1. The website doesn’t show the web logo in the email with social media information, slogan…
2. If you want to add an image in header or footer email template, he doesn’t appear in text editor or in email with code…
3. I think the email system can be better with some modifications or plugin integrations like Mailster…

Thank you very much, have a nice day!