The UNDRIP as a declaration has no legal nature and thus cannot be legally binding nor ratified, only adopted/supported.
The reasoning provided also references the fact that only 4 European countries have not adopted the UNDRIP as of 2018. This makes it clear that the intention was the ILO Convention, as virtually every European country except Azerbaijan and Georgia have adopted the UNDRIP, but only 4 have signed and ratified the ILO Convention as of 2017 (it is now 6, with Luxembourg (2018) and Germany (2021) recently having ratified it).
The delegates also confirmed so at the online session on May 3rd.