Adding new fonts?

Hi there

When I used Galaxy S3 I got a folder from this forum full of fonts.

Today, using S6 edge+ I'm using the same apk's and it says something like "unable to apply, uninstall? "

I'm currently using HiFont from playstore, but has not too good fonts in my opinion.

Is there any other way to add new fonts for our smartphone? Or even converting .ttf to .apk?

Thanks in advance!

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