If you are creating a PDF or a website, you need "embedding rights." Most standard desktop licenses do not permit you to convert the font to a web format (WOFF/WOFF2) without an additional Web License.
The standard DB Airy package supports Latin Extended (covering most Western and Central European languages). For Cyrillic or Greek, you would need a custom extension from Dalton Maag. db airy font download
After purchasing a web license, you will typically receive WOFF2 files. Upload them to your server and use: If you are creating a PDF or a
@font-face
font-family: 'DB Airy';
src: url('fonts/db-airy-regular.woff2') format('woff2');
font-weight: normal;
font-style: normal;