last Version in 12C LTS release of weblogic is 18.104.22.168 & was released on Sept 27, 2019
You can download the generic installer using below links:
Direct Link for generic Installer
When prompted login with your Oracle credentials, If you don’t have ID yet, you can create a free one with your personal e-mail id.
Once download is completed, use JDK to install weblogic using generic installer
java -jar fmw_22.214.171.124.0_wls.jar
In case you don’t have xserver installed, or not able to see GUI use silent install method.
java -jar fmw_126.96.36.199.0_wls.jar -silent -responseFile wls.rsp -invPtrLoc oraInst.loc
You can download sample response files from Oracle directly & modify as per your environment.