This seems easy but I spent some time googling it on the internet and did not find a straight answer.  I had to move my WordPress site to an AWS LightSail due to some technical issue with my previous web host and I didn’t know where to put my Ads.txt. 

To cut things short, AWS LightSail’s Linux + WordPress uses Bitnami and the root directory for its web server is on /OPT/BITNAMI/WORDPRESS.

Just drop your Ads.txt in that directory and you should be good. Once you have uploaded your Ads.txt, you should be able to access it using a browser by going to www.{}/ads.txt.

If you are using a different setup or prefer not to deal with technicalities, you can use a WordPress plugin. Login to your WordPress site and add the ‘File Manager‘ plugin. This plugin will show you the root directory of your WordPress site and from there you can upload to it directly.