device is htc legend with android 2.2
leo dictionary app can be installed but it does not work.
I installed on an old htc legend the leo dictionary app via play store. When I trying to use it, I get an error. Searching for it, I recognized, that dict.leo.org uses an letsencrypt certificat. The browser shows me, that it does not trust certificates from letsencrypt.
Question: How can I install the letsencrypt root zertificat on htc legend (android 2.2) that certificates released from letsencrypt may be fr leo will be trusted?
Thanks for your help.