There are several platforms that will help you.
1. ShoutMeLoud: This is a blog which screams being your own boss via blogging! Sounds interesting, right? It has a community of over 735+ bloggers who have contributed 1 or more guest posts. It familiarises its bloggers with nuances of WordPress, SEO, Google AdSense, Affiliate Marketing and more.
2. EduGorilla.com: A one-stop education community, it EduGorilla has over 120, 000 subscribers and over 500,00 monthly visitors. One of the best free guests posting websites, it invites posts from creative and indigenous writers and preferably writers from the education niche.
You can read more here: https://digest.myhq.in/13-free-guest-posting-sites-traffic/
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath