Can't disable submit or next button when Input form is incomplete

I created a slideshow with an input form. There are questions on each slide that the user needs to answer. Even though the required box is checked on for each input, the user is still able to hit the submit button without completing the entire form. Unfortunately, if the form is not complete, none of the information gets saved. I’d like to be able to disable the next or submit button if the form is not completed. Is there a code I could use to do this?

Check previous posts about it.
https://www.wix.com/corvid/forum/community-discussion/enable-a-form-submit-button-if-all-input-elements-are-valid
https://www.wix.com/corvid/forum/community-discussion/enable-disable-a-button-when-user-didn-t-fill-out-the-form
https://www.wix.com/corvid/forum/community-discussion/multiple-inputs-enable-and-disable-a-button

I checked out all of these forms. Unfortunately, I don’t know code well enough to insert it correctly. Every time I copy and paste something in, I run into an error and once I think I’ve found the error, I run into another. Is there a specific code you’d recommend for my problem.

It’s more than just copying and pasting codes. You have to know what to do with them to actually make them work. If you have already tried to read through the examples and explanations in those links, then the best think you can do is hire someone to teach you.