apex failure when trying the tutorial twilio-salesforce dialer

[eyal13579]

I opened a trial account and I'm trying to create a simple dialer with this tutorial

Thing is that first step of installing Twilio-Salesforce library (this url
is failing with

[Installing this package requires the following feature and its associated permissions: Apex Classes]
Apex Classes(classes/TwilioTRCapability.cls-meta.xml) Missing feature

triied to install to admins, to all users, nothing helps.
How exactly I install apex on a new trial salesforce env

[ygyoelito]

Something about this issue??? i have a same problem, two year before....