Between... and

Although the audience understand the message conveyed above, there is a grammatical mistake in the first sentence.
The preposition 'between' is wrongly used with the conjunction 'to'. It should be used with the conjunction 'and'.

When we want to indicate interval at periods of time, we use 'between...and'.

In the above context, it should be, 'You may encounter some difficulties boarding the train at this area between 8.00 am and 9.30 on Monday to Friday.'

'Between...and' is different from 'from to'.
'From to' is used when we want to emphasis the beginning and end of something. For example, 'They are giving away free handphones from 9am to 10am.'

Works Cited:

The Straits Times. (2007). English As It Is Broken. Singapore: Panpac Education Private Limited.