When uploading the file to Tomcat, please keep in mind that the file should be accessible via the standard ports - 80 (for a non-secure connection) or 443 (for a secure one). By default, Tomcat uses the 8080 and 8443 ports, respectively.
If the file will be accessible via the default Tomcat ports 8080 and 8443 only, the validation will not be completed.
The document root folder for the website on Tomcat can be found in the ‘server.xml’ file in the following line:
<Context path="/" docBase="/some/full/path/to/document/root/folder" />
Usually, the server root folder is located in the folder set under the variable $CATALINA_HOME, and the document root folder for the website is set to the particular folder under the server root folder.
You can create the ‘.well-known’ and ‘pki-validation’ folders for placing the validation file using the command line with standard Linux commands like mkdir for the folder creation and cd for navigating between the folders. Then, you can create the empty file with the exact name of your validation file with the command nano AN2D4C5H7F01823KRIDHJ.txt, copy and paste the full contents of the validation file into this file and save it with the standard Nano keys: Ctrl + O > Enter > Ctrl + X.