When you set up an Apache or LAMP Lightsail instance on Amazon Web Services, the default document root is /home/bitnami/htdocs/
If you are migrating to Lightsail already use something other than htdocs as your root folder, for example public_html, then you might want to update this.
Although you could creating a new app on the server to hand it, here is a simpler option which leaves the default folders and setup in place:
In /opt/bitnami/apache2/conf/bitnami/bitnami.conf add your own document root to the end of every location that htdocs is mentioned.
Then
sudo chown -R bitnami:daemon /home/bitnami/htdocs/*sudo chmod -R g+w /home/bitnami/htdocssudo /opt/bitnami/ctlscript.sh restart apache
And you should be good to go.