Adding a Checkbox group attribute

Hi,
I need to add several attributes to an event that are multiple choice so I need checkboxes. I was going to use event attributes but from what I saw I can get a dropdown of options but not a multiselect type of attribute. Is there a way to add a multiselect attribute without getting into the code?
What do you recommend is the best way to implement it?

Thanks in advance for your help!!

https://www.ads-software.com/extend/plugins/events-manager/