Hi,
I checked locally and creating a new environment using the conda-forge channel enabled me to run Spyder 4.2.5 with both plugins installed and available from the 'View > Panes' menu. Yo can run from an Anaconda prompt or terminal something like this:
conda create -n spyder4 -c conda-forge spyder=4.2.5 spyder-notebook spyder-terminal
However this is quite an old Spyder version so most probably you will face some issues while using it. Currently, the latest release for Spyder is 5.3.3, spyder-terminal is available for Spyder 5 and spyder-notebook is pending a release compatible with Spyder 5.
Let us know if the info above helps!
Best regards,
Daniel