Hello, everyone. 

I am new to Salesforce (I've began studying it about 1 month ago). 

There are some projects that I intend to implement on my Salesforce Professional Edition, but I am stuck due to some limitations. Since I don't have much experience with the platform, I wonder if the community of developpers could help me confirm if, in fact, my edition doesn't allow me to develop them, and if I need to upgrade my edition.

The implementations are described below:

1) Send scheduled email alerts

We want to send e-mail alerts when expiration dates of opportunities' contracts are approaching. In this context, we want to send weekly emails corresponding to each opportunity.

I've tried to do this by using Flow and Process Builder. Nevertheless, I always get the error message shown on this topic https://trailhead.salesforce.com/trailblazer-community/feed/0D54S00000BuOazSAF (bear with me...the french community seamed more active, so I tried to ask for help in french :) - google translator required). 

TL DR.: Error message = "insufficient access rights on cross-reference id"

2) Build a list of e-mails

The objective here is to make the sending of email messages more transparent. For example, if a sales representant sends an email to an opportunity, we want to make this message visible on Salesforce. At each opportunity page, there would be a "e-mails" tab, where we could show these messages.

3) Access data from external sources 

We want to access data contained on Google Cloud Big Query and Google Sheets. Note: We don't have access to Salesforce API on Professional Edition.


Actually, I think that the main question here is: 

What can developpers do on Salesforce Professional Edition? 

As a begginer, I am finding a lot of barriers. The things I was able to do so far are the following:

Change Pages' Layouts
Create New Objects and Fields
Create Email Alerts

Things I identified that I can't do:

Create Apex Classes
Create Customized Metadata
Access external API's