Licence and source code
Free software: you can use it, study it, share it and change it under the GNU General Public License, version 3 only.
The licence
Read the LICENSE. It's also installed with the app.
The source code
It's all in the repository on GitHub.
Third-party software
The libraries it includes, and their licences, are listed in THIRD_PARTY_NOTICES.md, also installed with the app.
The font on this website
Inter, under the SIL Open Font License 1.1, unchanged.
The name
"Apollo Download Manager" is the name of this app from Singlbase Technologies Limited.