When I try to instal the extension, I am asked to accept the same GPL3 license for the KNIME Extension for Big Data File Formats extension. If it is not the same for you, can you please share the screenshot of the license which is being prompted for you?
Also, can you confirm if you are using Windows or Mac also the KNIME version?
KNIME Extension for Big Data File Formats has GPL3. From my understanding you installed before this extension some other extension, where you accepted GPL3 already. Thus, you have not been prompted to accept that license again.
Now KNIME Extension for Big Data File Formats has dependencies on other plugins (i.e. it needs other pieces to be installed, too). One of them (KNIME Extension for Big Data Commons on Windows) has a different license. Your latest screenshot shows that KNIME Extension for Big Data Commons on Windows asks for this different license. So the KNIME Analytics Platform asks you to accept all licenses associated to the extension and its dependencies, if you have not accepted them before already (e.g. during installation of another extension).