Can I use the template for commercial purposes? For example Teachers pay teachers, my new videocourse, etc

Yes, of course. Provided you meet these two conditions:

• You give appropriate credit to SlidesCarnival.
• You’ve built upon the original material with your own content.

1. You are free to:

• Share — copy, add your own content and then redistribute the material in any medium or format
• Adapt — remix, transform, and build upon the material for any purpose, even commercially.

We cannot revoke these freedoms as long as you follow the license terms.

2. Under the following terms:

• Attribution — You must give appropriate credit and provide a link to this website. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
• No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.

3. Prohibitions

• You do not have the rights to resell, sublicense or redistribute (even for free) the files “as is” (without modifications) on its own or as a separate attachment from any of your work. You can only  resell/redistribute/attach a presentation made using SlidesCarnival templates if you’ve built upon the original material with your own content.
• If you wish to promote SlidesCarnival on your site, you must link back to the template page where users can find the “Use this template” link and not directly to the template file at Google Slides or Powerpoint.
• You can only use the templates for lawful purposes. Also, you can’t use a template with contents that are offensive, defamatory, pornographic, obscene or demeaning, or promote discrimination.